FR2699498A1 - A thermoplastic composite blade, particularly for a helicopter-mounted rear rotor, and its manufacturing process. - Google Patents

Abstract

The blade has its intrados (6a) and extrados (6b) coatings of its hull, its front (9) and rear (10) filler bodies and its spar (7) made of composite material having the same thermoplastic matrix, preferably PEEK, preferably reinforced with carbon fibers. The spar (7) is extended outside the hull by an integrated root portion with a connecting clip, looped or laminated, in the same thermoplastic composite. The process consists in assembling by fusion under pressure all the thermoplastic composite components of the blade, in a single operation, after manufacture of these components in the form of prefabricated elementary parts. Application to helicopter shrouded rear multi-blade rotor blades.

Description

i

  THERMOPLASTIC COMPOSITE BLADE, IN PARTICULAR FOR ROTOR

  REAR CARENE HELICOPTER, AND MANUFACTURING METHOD THEREOF

  The present invention relates to a blade, essentially

  made of composite material, for a rotorcraft rotor, and the invention relates more specifically to such a blade, the essential elements of which are made of composite matrix material made of a synthetic resin of

  stiffening, fiber reinforced, mineral or organic

  high mechanical strength.

  In a particularly advantageous application,

  such a blade is intended for the equipment of a multi-rotor

  blades with variable pitch and individually removable blades

  the rotor being usable, in particular, as a rotor

  rear, preferably faired, of a helicopter.

  The invention also relates to a method of

manufacture of such a blade.

  French patents FR-2542695 and FR-2616409 already disclose such blades, of the type comprising:

  a composite rigid hull with aerodynamic profile

  longitudinally elongated along the span of the blade, and a longitudinal end thereof, intended to be turned towards the hub of the rotor, has a blade root, said shell comprising at least one layer of

  reinforcement agglomerated by a matrix into a synthetic resin

  that of stiffening, at least one spar, at least a portion of which is housed substantially longitudinally in the shell, and comprising at least one elongate composite beam, continuous and unidirectional reinforcing fibers agglomerated by a matrix of a synthetic stiffening resin, and at least one filling body, arranged in the

  shell between the latter and at least one spar.

  Whereas in FR-2 542 695 each body of

  filling consists of a mass of synthetic

  Cellular or foam, and preferably adhesive, in an example of a blade described in FR-2,616,409, each filler body is also a composite body, comprising reinforcing fibers agglomerated by a matrix

  in a synthetic stiffening resin.

  Furthermore, it is known that the adoption of a multi-blade rotor, variable pitch and ducted, as helicopter rear rotor is very favorable for a helicopter with a total mass ranging in particular from 2 to 2.5 tons, since such a ducted rotor can offer at least the same performance as a conventional rear rotor, having a diameter twice as large as the ducted rotor, the latter having moreover predominant advantages both

  at the level of civil uses, at the level of security

  reliability and maintenance, as military, since it offers low vulnerability and low

radar signature.

  In order to be dismountable individually and with a variable pitch, each blade described in the aforementioned French patents comprises a root portion intended to be deformed in torsion about an axis substantially parallel to the longitudinal axis of the blade. , and by which the latter is attached to the hub of the rotor This root portion comprises at least one composite beam, elongated and torsion, which extends longitudinally, out of the shell, at least one composite beam of at least one spar, in passing through the blade root, which is tubular, the end of the torsion bundle of the root portion which is located on the side opposite the shell being looped around a coil removably attached to the hub by a bolt. the tubular blade root comprises a sleeve, metal or composite, whose axial ends are each surrounded by one of two coaxial flanges allowing the embedding and the rotational mounting of the blade root in two coaxial openings formed in two walls of the rotor hub, the sleeve further having, between these two collars, a

  pitch control lever, radially outwardly projecting

  and to be articulated to a collective control device of the pitch of the blades Inside the sleeve, the blade root is formed in part by extensions of the resin bonded fiber layers constituting the rigid shell of the blade, possibly by

  extensions of layers of agglomerated reinforcing fibers

  made by a synthetic resin, reinforcing the shell in its part adjacent to the blade root, and in part of filling elements and / or fiber fabric layers or sheets of synthetic resin bonded fibers

to strengthen the blade root.

  In the two aforementioned French patents, all the composite elements, in particular the shell, the longitudinal member (s), the root portion, at least partially the tubular blade root, and, optionally, the filling body (s), are produced in composite materials, based on polymerizable organic matrices, consisting of thermosetting synthetic resins, for example epoxy resins The reinforcing fibers of these composite materials are, for each blade, of different species, and in general of glass, of carbon, or even aramid fibers, and furthermore, these blades may comprise certain elements made of synthetic materials, but not

  composites, such as polyurethane foams.

  This results in a number of disadvantages.

  First, on the same blade, it may be necessary to use several thermosetting resins, each being adapted to particular reinforcing fibers, thus,

  possibly only synthetic elements that are not

  However, these different thermosetting resins

  In addition, the thermosetting matrices, under the effect of temperature and / or time undergo a chemical transformation called polymerization This reaction creates a modification

  of the molecular network, which becomes three-dimensional,

  fuse and irreversible During this thermal cycle, these thermosetting matrices pass successively in three stages: liquid, gel, solid The thermosetting matrix parts take their definitive form during the rise in temperature, just before the gelification of the matrix For example, for a matrix of the class of polymerizations said to 1800 C, this state is obtained at about 1600 C. Beyond, the matrix becomes solid, and the piece has

  taken in its final form This state is irreversible.

  This irreversible and infusible nature of the state resulting from a polymerization is at the origin of many difficulties of industrialization of these blades.

  scrap rate is important because the manufacturing processes

  of these blades, involving such polymerisation

  tion, are of a delicate and sometimes long implementation, and lead to obtaining blades which do not always have the required dimensional characteristics of

  the irreversibility of the polymerisation, the recyclability

  scrap is impossible, and repairs for refitting to the standard are long, expensive and delicate, when possible. The chemical reaction of polymerization can be at the origin of toxic gaseous releases, and the reactive nature of the products involved. poses problems of expiry and storage of these products Finally, it is known that thermosetting matrix composite materials have poor fatigue, shock and impact, temperature, and

  sensitivity to wet aging.

  The problem underlying the invention is to overcome the aforementioned drawbacks of the blades of the state of the

  technical and to propose blades which are sub-

  stituables, being of lower manufacturing cost and operating cost, while having improved reliability. Another object of the invention is to provide a blade whose structure and the realization at the level of the tubular blade root are extremely simplified compared to the embodiments described in the aforementioned FR-2,616,409 patent.

  For this purpose, the invention proposes a blade, essentially

  partially made of composite material, for a rotorcraft rotor, of the type presented above and as described in the aforementioned FR-2,616,409 patent, that is to say of the type comprising a composite rigid shell, at least one spar comprising at least one elongate composite beam, and at least one composite filler, and characterized in that

  resin of the matrices of the hull, each body of

  wise and each beam of each spar is a thermoplastic resin, ensuring the assembly and cohesion between them of the hull, the portion of each spar lodged

  in the hull, and each filler body.

  Thermoplastic die-based parts take their definitive forms at the time of the merger of

  the matrix over a temperature range of about 200 ° C above

  below the melting temperature proper At cooling, the matrix returns to its solid initial state, and the piece takes its final form.

is reversible.

  It is thus understood that the method of transforming composite materials with thermoplastic matrices, by simple melting or softening thereof under the effect of heating, and without chemical modification, allows higher production rates of blades made at the same time. of these materials It is all the more so that the polymerization operation, that the composites with thermosetting matrices undergo, after draping and implementation in a mold as described in the processes subject of the two French patents above, may vary in a range of 4 to 90 hours, depending on the nature and / or the thickness of the composites On the contrary, the thermoplastic matrix composites, which do not undergo a chemical reaction or exothermic during their transformation, and that whatever either their thickness, can be implemented quickly, and reversibly, by an elementary process, which, reduced to its simplest expressio n, consists in heating these composites to melt the matrix, to press these composites to compact them and / or to form, and then to cool them to consolidate their matrix. These thermoplastic composites can thus be transformed at a high rate. Their reversible character, such as

  mentioned above, offers possibilities for repairing

  By heating and then re-shaping the blades that do not comply with the specifications, for example dimensional, as well as recycling possibilities of the materials used. This results in a reduction of the rejects. Moreover, the matrix adheres hot to itself. is

  particularly advantageous since it allows not only

  to make localized repairs but also to

  as explained below, the manufacture of the blades by a process of assembling, by fusion of the

  die and under pressure, basic prefabricated

  a wide variety of processing techniques

  and assembly (compacting, stamping, pultrusion and injection in particular), from semi-finished products made of thermoplastic matrix composites and available in

trade.

  In addition, the absence of chemical reaction and exothermic reaction makes it possible to overcome the problems of air-conditioning of the blade manufacturing workshops and their components, as well as the problems of storage and

  expiry of the materials concerned.

  All of these factors contribute to a reduction in

  manufacturing and operating costs of the blades.

  To achieve the blades according to the invention, is advantageously selected a thermoplastic resin which is a polyether ether ketone resin (PEEK), and the reinforcing fibers, in particular the shell, or the longitudinal members, and the filling bodies, are chosen

  among the carbon or glass fibers, but preferably

  this, are all of the same nature, and in particular carbon. Advantageously, so-called "PEEK / carbon" thermoplastic composites are used, which, compared to the thermosetting composites of the blades of the state of the art, also have the advantages of a good general mechanical behavior in static, and a better resistance to fatigue, a good tolerance to damage and a high resistance to the environment, and in particular insensitivity to wet aging, very good temperature resistance, as well as shocks and impacts.

  In addition, the choice of a PEEK matrix makes it possible to obtain

  good creep behavior and improves fatigue performance, which is at least twice

  various other high performance thermoplastic matrices

  these known and used for the production of composite materials in other applications The choice of a single PEEK resin as a matrix and reinforcing fibers only carbon, or possibly only glass, to achieve the various composite elements of the blade avoids any disparity in the agglomeration resins and any risk of incompatibility between the different constituents, unlike the blades described in the patent FR-2,616,409 cited above, in which each thermosetting resin used is adapted to the nature of the fibers reinforcement, made of glass, carbon or aramid, that she

  agglomerate, as well as the nature of the material (s)

  theories, for example polyurethane foam, with

  which it is put in contact.

  The PEEK / carbon thermoplastic composites thus have advantages of behavior in use which result from remarkable thermomechanical properties, at least of the same order of magnitude, but often even superior to those of many composite materials with thermosetting matrices used for the realization

  blades of the state of the art.

  It is thus understood that it leads to a reduction in the cost of manufacture and maintenance and an improvement of the blades according to the invention compared to

those of the state of the art.

  In order to simplify the realization of the blade from prefabricated elementary parts, made of composite material of the same nature, it is advantageous that, moreover, each filler body of the blade is composite and

  consisting of continuous and unidirectional reinforcing fibers

  the, advantageously oriented substantially parallel to the longitudinal axis of the blade, and preferably carbon, agglomerated by said thermoplastic resin, preferably

a PEEK resin.

  In particular, when the blade retains a rope

  substantially constant in its aerodynamically profiled portion

  that, as is generally the case of the blades of the helicopter rear rotor blades, each filler is advantageously a profiled pultruded said fibers

  continuous and unidirectional in said thermal resin

  moplastique. As already known from the aforementioned French patents, the hull of the blade may comprise laminated extrados and intrados coatings extending from the leading edge to the trailing edge of the blade. In this case, each laminated coating advantageously comprises several superposed layers of reinforcing fibers, each layer of which is a fiber fabric or a web of continuous fibers and

  unidirectional, agglomerated in the thermoplastic resin

  than. In particular, in a preferred embodiment, offering a good compromise between the rigidity of the shell and the cost and volume of the constituent materials, each

  laminate coating includes, from the inside to the outside

  of the hull, two layers of long and unidirectional fibers

  oriented substantially along the longitudinal axis of the blade, and covered with at least one layer of fiber fabric, the directions of the weft and warp threads are oriented substantially at 450 relative to the longitudinal axis of the blade. blade. Similarly, when the blade root is tubular, and, as known from the aforementioned French patents, extends the shell substantially axially, it is advantageous, in order to achieve this foot of blade more simply than in the aforementioned French patents, that, according to the invention, the tubular blade root is, at least in part, consisting of two complementary half-shells, each of which is constituted

  by an extension of one respectively of the two

stratified

  In this case, in order to allow a good rigid connection of the tubular blade root, on the one hand, to the rest of the blade, and, on the other hand, to the other components mounted at the blade root for the transmission of torque pitch control at the hull of the blade, each laminated coating is advantageously reinforced, at the level of said

  corresponding extension, by at least one layer

  fiber fabric, of which one of the directions of the warp and weft threads is substantially oriented

  along the longitudinal axis of the blade.

  Similarly, as already known from the aforementioned French patents, at least one elongate composite beam of at least one spar, but preferably each beam of each spar, is constituted by at least one blade formed by

  agglomeration by resin and side by side or in

  several layers of continuous and unidirectional fibers

  substantially oriented along the longitudinal axis of the blade. It is then advantageous that said blade is not twisted in the shell according to the span, and around said longitudinal axis of the blade, and that it has a substantially rectangular cross section, at least in his

  part adjacent to the blade root and internal to the hull.

  Such an embodiment, in which the largest dimension of the transverse section of the beam of the spar extends in the plane of rotation of the rotor, makes it possible to facilitate the realization of the fastening means and attachment of the spar to the hub, without preventing to a certain extent, a particular angular position of the profiled coverings of the shell with respect to the rectilinear spar blade. But this beam of the spar can also have a cruciform cross section, on part of its

  internal length to the hull and adjacent to the blade tip.

  This makes it possible to twist the hull of the blade without distortion.

  the spar at this level such a cross section

  stabilizes the intrados and extra-

  back on the two end faces of the spar blade, during the assembly operation of the various elements of the blade.

  Whether the blade is cruciform or rectangular

  gular, its non-twisted character according to the span is favorable for the manufacture of the blade, while providing the stiffness required at this blade, which is surrounded by the shell and the filling body or bodies, which are advantageously twisted around of the longitudinal axis of change of pitch of the blade, located at about 40% on the rope from the leading edge of the blade Thus, the pitch axis of the blade is also a twisting axis of the sections of the blade. profiled blades around a non-twisted spar blade It is thus possible to give the blade the law of evolution of the desired aerodynamic profile around a spar with a non-twisted blade (s), the manufacture of which does not

is not complicated.

  As already mentioned above, the blade according to the invention is essentially intended to be substitutable for the blades described in the aforementioned French patents. As a result, this blade is in particular intended to equip a multi-blade rotor with blades that can be dismounted individually. and it can be used as tail rotor, preferably ducted, helicopter For this purpose, the blade may be of the type which comprises a portion of blade root, comprising at least one blade attachment beam which is elongate, composite, and torsionally about its longitudinal axis, and which extends, outside the shell, while passing through the tubular blade root, at least one composite beam of at least one spar of longitudinal axis substantially parallel to that of the blade , the end of each attachment beam, on the opposite side to the hull, being arranged as a connecting link to a rotor hub In this case, the blade according to the invention is characterized in that each attachment beam of the root part is in one piece with the composite beam of the spar, and consists of the same reinforcing fibers agglomerated by the same thermoplastic resin. In a first variant, at least one spar consists of a skein of continuous reinforcing fibers and

  unidirectional, agglomerated by said thermal resin

  moplastic, and which has two substantially parallel portions to each other and to the longitudinal axis of the blade, which constitute two beams of spar received in the hull, and connected to one another by a portion of substantially flattened loop, which constitutes the root portion, the looped end of which forms a hub-connection loop fastener, to surround a sleeve by which the blade is intended to be individually removably attached to the hub by a bolt, said loop fastener being connected to said sill beams received in the shell by two skein portions forming two torsionary tie beams of the root portion. This first variant thus comprises a loop fastener, or wound, geometrically similar to that of the blades described in the two aforementioned French patents, so that the blade according to the invention is directly substitutable, on a rotor hub as described in

FR-2,542,695.

  According to a second variant, the connection fastener to the hub of at least one fastening bundle is a laminated fastener, comprising at least two laminated elements between which a connecting end portion of the fastening bundle, on the opposite side to the shell, is sandwiched and secured, each laminated element comprising a stack of at least two layers of the same reinforcing fibers as those of the fastening bundle, agglomerated by said thermoplastic resin, which secures said laminated elements to said portion connecting end, the laminated fastener being shaped to abut towards the shell, against removable means for retaining the

  the flap fastener and the blade to the hub.

  This second variant corresponds to a blade provided with a laminated fastener identical in its mode of operation and in its basic structure, and even, possibly, in its geometry, to that described in the joint patent application in the name of the Applicant entitled "Blade-hub connection device laminated fastener, rotor blade provided with such a fastener, and rotor equipped with such blades" It is thus understood that the blades according to this second variant of the invention are substitutable for those described in both aforementioned French patents, subject to providing the hub and means for connecting and retaining blades on the hub, the arrangements that are described for this purpose in the application

aforementioned patent joint.

  The invention thus allows an alternative of

  binding ties at the end of the bundles

  torsibles of the root part of the blades.

  When the blade comprises a laminated connection fastener, it is advantageous, to facilitate the realization of the root part and the corresponding spar, that each fastener bundle comprises at least one pultruded blade of continuous and unidirectional fibers in said thermoplastic resin , said fibers being oriented substantially along the longitudinal axis of the beam

  fastener, and each laminated element of the fastener

  sheet comprises a stack of several crossed webs of continuous and unidirectional fibers and / or layers of fiber fabrics, so that the directions of the fibers are substantially at 450 relative to the longitudinal axis

the attachment beam.

  In a preferred embodiment according to this variant, the root part of the blade comprises at

  at least two twisted beams, which gradually

  from one another in the direction of a common laminated fastener, and from a single beam of spar lodged in the shell With respect to the loop-fastening variant

  or rolled up, as mentioned above, this

  The advantage of using two twisted beams is that it makes it possible to minimize the difference between the beams, hence a substantial reduction, by a factor of the order of 2, and also related to the use, preferably, of carbon reinforcement fibers in a PEEK thermoplastic matrix,

  the control effort necessary to ensure the variations

  footsteps or aerodynamic impacts of the blade, on

the whole range of steps.

  In order to facilitate the realization of this preferred example, each of the twisted beams is preferably

  consisting of part of the length of a respective

  several pultruded fiber boards and

  unidirectional agglomerated in said thermal resin

  moplastic, these different blades being applied against each other over the rest of their length, with interposition of at least one ply of the same continuous and unidirectional reinforcing fibers, having the same orientation along the axis of the blade, and agglomerated by the same resin, between two adjacent blades, to form the

  part of spar lodged in the hull.

  When the blade according to the invention is intended to equip a multi-blade rotor, whose blades are moreover variable pitch, it is advantageously of a type known from the two aforementioned French patents, and such that the blade root comprises a bearing embedding and rotation of the blade root on a hub, said bearing comprising a blade root sleeve which has, radially outwardly projecting, a pitch control lever, intended to be articulated to a control device collective collective pitch of the rotor blades But, according to the invention, in order to simplify the realization of this bearing, the sleeve is a tubular sleeve molded composite short reinforcing fibers, glass or carbon, embedded in the same thermoplastic matrix that the other composite components of the blade, this sleeve preferably having, over at least a part of its length, a general internal and external frustoconical shape with a large base turned towards the shell Of course, it it is also possible to use a metal sleeve, for example of light alloy, reported and glued or hooped around the tubular blade root, but the use of a molded short carbon fiber sleeve for example in a PEEK resin allows a very appreciable gain in mass without substantial decrease in mechanical characteristics To improve the rotation of the flange foot mounting bearing on the hub, the sleeve is preferably integrally surrounded, at each of its axial end portions, by the one respectively of two metal or ceramic rings,

  forming rotational bearings of the sleeve on the hub.

  In order to give the blade root all the torsional stiffness necessary for a good transmission of the pitch control forces, it is advantageous that the blade root also comprises an internal reinforcing cuff, also molded from a composite of short reinforcing fibers,

  glass or carbon, embedded in the same thermoplastic resin

  tick, the central passage of said sleeve, traversed by the root portion of the blade, then preferably

  frustoconical shape with a small base turned towards the hull.

  This form of the internal passage of the sleeve allows the latter to occupy a relatively large volume inside the blade root without interfering however with the movements in torsion and possibly bending of the

  part of root that crosses it.

  The subject of the invention is also a process for manufacturing the blade which is the subject of this

  request, and as presented above.

  At the level of the method, the idea underlying the invention is to take advantage of the reversibility property of a thermoplastic matrix, that is to say that it suffices to heat it to melt the matrix, then to cool it to solidify it, and this as many times as desired, and also to take advantage of the

  property of thermoplastic matrices to adhere to them

  even when they are melted, to make a blade

  essentially made of thermoplastic matrix composite material

  by assembling, in a single operation, all the thermoplastic composite components of the blade, these

  components each having been previously manufactured.

  More specifically, the method of manufacturing a

  blade according to the invention, the composite hull of which is

  characterized by the fact that it comprises the following steps consisting of: producing each of the thermoplastic composite components of the blade in the form of a part. prefabricated elementary element, disposing the prefabricated elementary parts in a pressurized heating assembly mold, comprising a lower mold part and a part of

  upper mold with internal impressions

  complementary, respectively presenting the shape of the intrados portion and the extrados portion of the blade, so that said prefabricated elementary pieces occupy in the mold the respective positions they occupy in the blade, to close the mold and heating said parts to a temperature sufficient to melt the thermoplastic matrix at a pressure sufficient to ensure the continuity of the thermoplastic matrix between said parts and their assembly by melting under pressure;

  to cool the mold, to ensure the solidification

  of the thermoplastic matrix and the stiffening of the assembly of the elementary pieces thus assembled, to unmold the blade thus obtained, and to bring rings, by gluing or by hooping, around a blade root sleeve, itself reported, by gluing or hooping, around said blade root if it is not a thermoplastic composite and already assembled by pressure fusion to the other elementary parts

prefabricated of the blade.

  The method may also comprise a step consisting in fixing, for example by gluing, a leading edge protection, for example made of titanium, on the demolded blade. However, in a variant, the leading edge protection

  can be introduced into the assembly mold by heating

  fage under pressure, before the closure of the latter, and be fixed to the blade by adhesion, following the merger then

  cooling the thermoplastic matrix.

  The various prefabricated elementary pieces can be made in the form of rigid elements, having a cardboardy appearance, or semirigid, having the appearance of sheets or plates, without tack, possibly with

  from thermoplastic composite semi-finished products

  commercially available, such as continuous or long fiber and / or unidirectional fibers of glass or preferably of carbon, agglomerated with a thermoplastic resin, preferably a PEEK resin, or plates obtained by superposition and then compacting of several layers of such fabrics or such plies, or short reinforcing fiber granules contained in the dry state in a thermoplastic matrix, for example short carbon fibers in a PEEK matrix, these granules constituting a melt injectable composite material

of the matrix.

  Thus, the blade according to the invention comprises one or more thermoplastic composite filling bodies housed in the shell, between the latter and at least one spar, the method according to the application further comprises

  the step of making the basic piece cor-

  corresponding to each filling body by pultrusion of a profile of continuous and unidirectional fibers,

  preferably carbon, agglomerated in a thermal matrix

moplastic, preferably PEEK.

  With regard to the production of each of the lower and lower surfaces of the shell, the method according to the invention furthermore comprises the step consisting in producing the elementary piece corresponding to a laminate coating of the lower or upper surface of the shell. shell by stamping forming, between two mold parts maintained at a temperature below the melting temperature of the matrix, and having complementary impressions corresponding to the shape of the laminate coating considered, a panel preheated to a temperature of matrix fusion, having the flat developed form of the coating

  laminate considered, and cut from a precompact

  obtained by stacking several layers of fabrics and / or plies of continuous and unidirectional reinforcing fibers agglomerated by the matrix, under pressure and at a melting temperature of the matrix, and then stiffening into

  plate by solidification of the matrix by cooling.

  In order to manufacture a blade according to the invention, whose blade root is equipped with a pitch control sleeve, also made of a thermoplastic matrix composite, the method according to the invention furthermore comprises the step of producing the elementary piece constituting the sleeve by

  injection molding, in a heated mold at a temperature of

  less than the melting temperature of the matrix, a composite material consisting of short reinforcing fibers, preferably carbon, embedded in a matrix

  molten thermoplastic, preferably a PEEK matrix.

  Similarly, in order to manufacture a blade according to the invention, the tubular blade root of which is reinforced by an internal reinforcing cuff, also made of a thermoplastic matrix composite, the method according to the invention further comprises the step of carrying out the elementary piece constituting the sleeve by molding by

  injection, in a mold heated to a temperature

  lower than the melting temperature of the matrix, a composite material also consisting of short reinforcing fibers, preferably carbon, embedded in a matrix

  molten thermoplastic, preferably a PEEK matrix.

  In order to injection mold the pitch control sleeve and / or the blade root reinforcement sleeve, the reinforcing short fiber composite material embedded in a molten thermoplastic matrix is advantageously obtained by heating up to the fusion of said matrix, granules of short fibers contained in the dry state in said matrix, which is loaded at about 30% by mass of the short fibers, the heating of the granules being preferably carried out after steaming of the granules at a temperature of order of 1500 C for at least three hours It is thus advantageously possible to make the sleeve and / or the sleeve from the granules, which constitute

  semi-finished products available commercially.

  Although the pitch control sleeve and the injected composite blade foot sleeve are advantageously assembled by pressure melting to the other thermoplastic composite components of the blade, by the method of the invention and mentioned above, it is it is also possible for these two elements to be attached by gluing to the other assembled components of

the blade.

  To manufacture a blade according to the invention, having at least one thermoplastic composite spar, a part of which is external to the shell constitutes a part of blade root with two fastening beams forming a loop fastening connection to the hub and prolonging at least one spar beam housed in the shell, the method according to the invention further comprises the step of

  the elementary piece constituting said spar by winding

  a ribbon of continuous and unidirectional reinforcing fibers

  formed in said thermoplastic matrix, in several layers and under mechanical tension around two coils, then by forming in a mold by

  compaction of the winding under pressure and at a temperature of

  melting of the die, followed by solidification cooling of the die, and cutting of an end portion of the winding on the opposite side of the loop fastener. On the other hand, to manufacture a blade according to the invention having the other type of hub connection fastener, as presented above, that is to say a blade having at least one thermoplastic composite spar, of which a portion external to the shell constitutes a blade root part with at least one attachment bundle, a hub-connecting end portion of which is provided with a laminate fastener, also made of thermoplastic composite, and extending a bundle of a spar lodged in the hull, the method according to the invention furthermore comprises the step consisting in producing the elementary piece constituting this spar by producing each attachment beam and the beam of spar that it extends in the form of a blade of continuous and unidirectional reinforcing fibers agglomerated in said thermoplastic matrix, obtained by pultrusion at a matrix melting temperature, of several plies of unidirectional continuous and unidirectional fibers in this matrix, and, if said root portion comprises at least two attachment beams, each of which respectively extends a beam of a spar, to superimpose portions of the corresponding blades intended to form the spar portion housed in the shell, with interposing at least one ply of continuous and unidirectional fibers agglomerated in said matrix between overlapping portions of adjacent blades, and providing wedge-shaped removable tooling between portions to be spaced apart from one another; another of two adjacent blades, to form two fastening beams of the root portion, then to arrange the blade or blades in a mold, and to insert each connecting end portion of a pultruded blade between two laminated elements the fastener, so as to superimpose all the laminated elements of said fastener, to close the mold and to compact its contents under pressure and at a melting temperature of e said thermoplastic matrix, to then solidify the matrix by cooling to stiffen the spar thus obtained with the laminated fastener secured to its root portion. In the latter case, the method according to the invention also consists in producing each laminated element of the thermoplastic composite laminated fastener by stacking several layers of fabrics and / or unidirectional continuous and unidirectional fiber plies in said thermoplastic matrix, compacting the stack thus obtained under pressure and at a melting temperature of the matrix, solidifying the matrix by cooling to obtain a compacted plate, and cutting said

  laminated element in said compacted plate.

  The invention will be better understood, and other features and advantages of the invention will become apparent.

  reading the description given below of an example

  embodiment, described by way of non-limiting example and with reference to the accompanying drawings, in which: FIG. 1 is a side elevational view of a blade for a multi-blade, variable pitch, rear and hulled helicopter rotor, FIG. is a plan view, according to the arrow F of FIG. 1, of this blade,

  FIGS. 3 to 7 are cross-sectional views

  respectively according to III-III, IV-IV, V-V, VI-VI and VII-

  VII of Figure 2, Figure 8 is a schematic axial sectional view of the foot of the blade of Figures 1 and 2, Figure 9 is a partial perspective view of the blade root, the root portion and the FIG. 10 is a view similar to FIG. 9 of an alternative embodiment, in which the blade spar has been modified so that its root portion has a fastener. in a loop, in place of the laminated fastener, FIG. 11 is a plan view of a precompacted plate in which are cut panels for intrados and extrados covering of the hull of the blade of FIGS. 9, Figures 12 and 13 show diagrammatically two steps of embossing the lower and upper surfaces, Figure 14 shows schematically a stamped coating in side elevation, Figure 15 shows the plan facing along the arrow F of the figure 14, Figures 16, 17 and 18 show cross-sectional views respectively according to XVI-XVI, XVII-XVII, XVIII-XVIII of Figure 15, Figure 19 shows in plan a precompacted plate in which are cut out laminated elements of the laminated fastener of the blade according to FIGS. 1 to 9, FIGS. 20 and 21 schematically represent steps in the manufacture of the laminated beam spar of the blade according to FIGS. 1 to 9, FIGS. 22 and 23 schematically represent respectively in plan and in lateral elevation, the spar made, FIGS. 24, 25 and 26 represent cross-sectional views, respectively according to XXIV-XXIV, XXV-XXV, XXVI-XXV I of FIG. 23, and FIG. putting into place the various thermoplastic composite components of the blade of FIGS. 1 to 9 in a mold for melting under pressure, for producing the blade with

  from prefabricated components.

  The blade 1 of FIGS. 1 to 9 is a blade whose running or profiled part 2 extends, on the opposite side to the blade tip 3, by a tubular blade root 4, which is traversed by a root part 5, by which the blade 1 is intended to be connected to a rotor hub (not shown), and which is constituted by an outer portion to the current portion 2, of a spar 7 extending over any

the span of the blade 1.

  In its running part 2, the blade 1 comprises a rigid shell 6, having the shape of the desired aerodynamic profile, and lengthened longitudinally along the span of the blade, the spar 7, a rectilinear portion of which is housed longitudinally in the shell 6, according to the span of the blade, and which is substantially centered on the longitudinal axis AA of the blade, which is the axis of change of pitch of the blade, about 40% in rope from the leading edge 8 of the blade, a front filling body 9, housed in the shell 6, between the spar 7 and the leading edge 8 of the blade, and a rear filler body 10 housed in the shell 6, between the spar 7 and the trailing edge 11 of this blade. In its current portion 2, the blade may also comprise a cap (not shown), made of titanium or stainless steel, for the protection of the leading edge 8 of the blade. The portion of the spar 7 housed in the shell 6 has a cross section of substantially rectangular shape, the largest dimension is directed along the rope of the blade, or contained substantially in the plane of rotation of the blade and perpendicular to the axis longitudinal AA of the blade, and this at least in the spar portion 7 internal to the shell 6 and adjacent the blade root 4, as shown in Figures 3 and 5, although this portion of spar 7 may have such

  rectangular cross section to the blade tip 3.

  However, as shown in Figure 4, and at least in the vicinity of the blade tip 3, the spar 7 may have a cruciform cross section As the rigid shell 6 consists of a lining 6a and a coating of extrados 6b, which each extend from the leading edge 8 to the trailing edge II of the blade, the cross section of the spar 7 makes it possible to stabilize the coatings 6a and 6b on the two end faces of the spar 7 which are directly opposite these coatings 6a and 6b, during the assembly operation by melting under pressure of the various components of the blade, as described below with particular reference to Figure 27 That its section is substantially rectangular or cruciform, the spar 7 is not twisted according to the span of the blade, and around the pitch change axis AA of the blade, which is favorable for its manufacture while allowing to give it the required stiffness However, the profile section e coatings 6a and 6b as well as front and rear filler bodies 10 is progressively twisted about the axis AA of the blade, to give the latter the desired twist law, since the portion of the current portion 2 adjacent to the blade root 4 to the blade tip 3, and as schematically shown in Figures 3 and 4 Thus, the pre-calibration of the blade 1 is very easy to create relative to the plane of rotation of the rotor. Each coating 6a or 6b of the shell 6 is laminated and constituted, from the inside to the outside of the shell 6, advantageously a stack of two layers of continuous and unidirectional carbon fiber layers, oriented substantially according to the longitudinal axis AA

  of the blade, and agglomerated in a matrix of polyether-

  ether-ketone commonly called PEEK resin, and a layer of carbon fiber fabric, agglomerated in the same PEEK resin, and whose warp and weft son directions are oriented substantially at 450 relative to the longitudinal axis The PEEK resin is a thermoplastic polymer with an aromatic structure, having few hydrogen atoms, and having a structure

  crystalline, a glass transition temperature of about

  150 ° C., and a melting temperature of the order of 3900 C. This polymer is used in particular as a matrix for thermoplastic composites mainly reinforced with carbon fibers, and secondarily in fiberglass, which

  are available on the market in the form of

  products such as webs of continuous or long and unidirectional reinforcing fibers agglomerated with PEEK resin, and having a reinforcing volume ratio of the order of 50%, reinforcing fiber fabrics agglomerated with this PEEK resin, or alternatively granules of this resin in which are embedded short carbon fibers, these semi-products being more precisely described below in

  relationship with the manufacturing process of the blade.

Alternatively, each of the laminate coverings 6a and 6b of the shell 6 may consist of a stack comprising more than one layer of carbon fiber fabric, over the two layers of unidirectional carbon fiber webs. regardless of the number of layers of fibers forming the stratified stack of each coating 6a or 6b, all of these layers are agglomerated by the stiffened PEEK resin, so as to form a box ensuring, with its filling, the rigidity in torsion of the

pale 1.

  The front and rear filler bodies 9 each consist of a pultruded profile of continuous and unidirectional carbon fibers, oriented substantially parallel to the longitudinal axis A-A of the blade, and

agglomerated with PEEK resin.

  The spar 7 consists of a single composite and elongated skein of continuous and unidirectional carbon fibers, oriented longitudinally along the axis AA of the blade, and also agglomerated by PEEK resin This skein is arranged in the shell 2, in an elongate blade of solid section, having, as already said, a rectangular or cruciform shape in a portion more or less

  long, on the side of the blade tip 3, but still

  In the portion adjacent to the blade root 4 of the upper and lower faces of this skein, the spar 7 is rigidly connected, either directly or via the composite filling bodies of the same nature 9 and 10, to the hull. Rigid 6 in which it is received This skein is extended axially outside the shell 6, through the tubular blade root 4, and thus forms, by its part that leaves the profiled portion 2 of the blade 1, the part of root 5 of this blade At the transition zone 12, by which the shell 2 is connected to the tubular blade root 4, which extends it

  axially, the elongated composite skein of rectangular section

  the longitudinal member 7 is subdivided into two equal beams 13a and 13b, each also having the shape of a blade of

  rectangular cross section, which deviate progressively

  one of the other in a direction perpendicular to the largest dimension of their rectangular sections, as well as that of the rectangular part of the spar 7 in the shell 6 At the axial end of the part of 5, on the side opposite to the blade root 4, the two rectangular blade beams 13a and 13b of this

  part of root 5 each have a portion of

  linkage 14a or 14b, parallel to the connecting end portion of the other beam 13a or 13b, and by which each of the beams 13a and 13b is secured to a common laminated fastener 15, which constituting the connecting link of the root portion 5 to a rotor hub (not shown). The two blade attachment beams 13a and 13b of the root part 5, which are extended substantially in the extension. longitudinal of the shell 6 and the spar portion 7 internal to this shell, so each have the same composite structure as the spar portion 7 internal to the shell 6, with which they are in one piece, and each of the beams 13a and 13b is twistable about its longitudinal axis, so that the root portion 5 is itself twisted around

  of the longitudinal axis A-A of the blade 1.

  Such a blade, with a root portion consisting of several elongated and torsion composite beams, the end portions of which are connected to the hub are integral with the same laminated fastener, for the connection to a rotor hub whose structure comprises means adapted to the retention of such a laminated fastener, is more specifically described in the aforementioned joint application of the applicant, which will be referred to for more details on the realization of the laminated fastener and on the hub structure and editing

  the flap fastener on the hub.

  It will be recalled that the laminated fastener 15 comprises a lower laminated element 15a, an upper laminated element 15b and an interlayered laminated element 15c, which are arranged vertically above one another, so that the portion of The connecting end 14a of the lower blade 13a is sandwiched between the lower laminate elements 15a and 15c, and the connecting end portion 14b of the upper blade 13b is sandwiched between the Each of the laminated elements a, 15b and 15c consists of a stack of several layers of carbon fiber fabric bonded with PEEK resin, and whose yarn directions of warp and weft are oriented substantially at 450 relative to the longitudinal axis of the blade 13a or 13b, or a stack of

  several layers of continuous and unidirectional fiber sheets

  carbon layers agglomerated with PEEK resin, the plies being alternately crossed relative to one another in the stack, so that the direction of the unidirectional fibers of a ply is substantially perpendicular to the direction of the fibers of the one or more adjacent layers, the orientation of the layers of the stack

  being such that the unidirectional fibers of the

  these webs extend substantially 450 relative to the longitudinal axis of the beam lamina 13a or 13b. For example, each of the lower laminate elements a and b may be constituted by the stack of nine layers of fabric or sixteen layers or, alternatively, a stack comprising layers of fabric and layers of

  The interlayer laminated element 15 c is a stack of

  it consists of the same layers of fabric and / or layers of plies, but whose thickness is twice that of the lower laminate elements 15 a and upper 15 b, the intermediate element 15 c being for example made by superimposing two laminated elements such as that the elements

lower 15a or higher b.

  As shown in FIG. 2 and, in more detail, in FIG. 9, the three laminated elements 15a, 15b and 15c have, seen in plan, the same flared shape laterally on both sides of the end portions of FIG. 14a and 14b, which are substantially rectangular in the extension and at the end of

blades 13a and 13b.

  The laterally flared shape of the two sides of each laminated element 15a, 15b and 15c with respect to the connecting end portions 14a and 14b is delimited by the lateral faces of these elements, which project laterally by relative to the end portions 14a and 14b, and which have, in the portion of each laminated element which faces the shell 6 of the blade, a concave zone 16, concavity turned laterally on one side or the other. other of the blade and towards the shell 6, while in the end portion of the laminated elements 15a, 15b and c which is turned on the opposite side to the shell 6, the lateral faces of these laminated elements have zones planes 17 which converge towards each other, delimiting on the laminated elements a shape end portion

substantially trapezoidal. In order to fill the space delimited between two laminated elements 15 a, 15

  b and 15 c neighbors, by the portions of these two adjacent elements which project from the connecting end portions 14a and 14b, the laminated fastener 15 also comprises four lateral filling laminated elements, two of which, 18a (see FIG. 9) are each placed in abutment against one of the lateral faces of the connecting end portion 14a, and sandwiched between the projecting lateral parts of the lower laminate elements 15a and 15c, and whose two others 18b are each placed in abutment against one of the lateral faces of the connecting end portion 14b and sandwiched between the laterally projecting parts of the interlayer 15c and upper laminated elements 15b The laminated filling elements side 18 a and 18 b are of a laminated structure similar to that of the other laminated elements 15 a, 15 b, 15 c, thus composite PEEK / carbon, and their side face o applied to that by which they are each applied against one of the connecting end portions 14a and 14b also has, as the side faces of the laminated elements 15a, 15b and 15c, a concave zone 19, which is an extension of the concave areas 16 of the laminated elements 15a, 15b and 15c, and a planar zone 20, which is an extension of the planar zones 17 of the laminated elements 15a, 15b, 15c, and which is therefore convergent with the flat area 20 of the other element

  laminated lateral filling 18 a or 18 b corresponding.

  The joining of all the laminated elements a, 15b, 15c, 18a, 18b of the laminated fastener 15 to the connecting end portions 14a and 14b of the two twisted blades 13a and 13b of the part 5 of the blade 1 is provided by the stiffening of the PEEK resin, which agglomerates all the carbon reinforcing fibers, in layers of layers of unidirectional fibers or fabric, which constitute the laminated elements of the fastener 15 as well as that the twisted blades 13a and 13b and their portions

  link end 14a, 14b.

  In order to facilitate the production of the spar 7, with integrated root portion 5, the single composite skein of the spar 7 is formed of two beams of the same nature, each consisting of a pultruded blade comprising a plurality of superposed layers of continuous and unidirectional fibers of carbon oriented along the axis AA of the blade, and agglomerated by PEEK resin, the different layers of superposed fibers of each blade can be obtained by superposition of an equal number of the same lengths cut in a PEEK / carbon composite tape,

  with unidirectional and longitudinal carbon fibers.

  The two pultruded blades are kept spaced from each other over a part of their length, which forms the root part 5, thanks to the laminated fastener 15, which they are secured by their corresponding end, while on the rest of their length, these two pultruded blades are superimposed, with the interposition of three layers of unidirectional and longitudinal carbon fibers agglomerated by the PEEK resin, to constitute the part of the

spar 7 received in the hull 6.

  In use, the centrifugal forces exerted on the blade 1 urge the spar 7 longitudinally, so that its laminated fastener 15 abuts, by the concave recesses formed laterally on both sides by the side faces 16 and 19 of its elements. laminates, against sockets, at least one of which is removable to allow individual disassembly of the blade, which are secured to the hub, and each located on one side of the root part 5, extending into a direction substantially perpendicular to the plane of rotation of the blade, which plane of rotation is substantially parallel to the large upper and lower faces of the laminated elements and the twisted blades of the part

root 5.

  The tubular blade root 4, represented schematically

  Figure 8, comprises two complementary half-shells 21a and 21b, each of which is in the form of half of a tube, of variable section, cut axially by a diametral plane, and these two half-shells 21a and 21b

  are joined one against the other by their long edges.

  longitudinal, so as to reconstitute the tube section, and are each constituted by an axial extension of one respectively of the two laminated coverings 6a and 6b of the hull 6 of the blade Each half-shell 21a or 21b is laminated and comprises not only the different layers of fabric and plies of fibers agglomerated by the PEEK resin which constitute the coating 6a or 6b that it extends,

  but at least one additional layer of reinforcement, local

  at the level of this extension, and which is for example a layer of PEEK / carbon fabric, the directions of the warp and weft son are one substantially parallel and

  the other substantially perpendicular to the longitudinal axis A-

  In the blade, this or these layers of additional reinforcement

  coming over the other layers of the coating.

  In order to stiffen the blade root 4 by giving it a sufficient thickness, these two half-shells 21a and 21b

  are internally reinforced by a tubular sleeve 22

  This sleeve 22 has an axial and central passage 23, which is traversed by the two blades 13a and 13b of the root portion 5, close and at their subdivision from the beam member 7 in the shell 6, and this central passage 23 is delimited by an internal lateral surface of generally frustoconical general shape, with a small base turned towards the shell 6 The sleeve 22 furthermore has an external lateral surface of general shape also substantially frustoconical, but with a large base turned towards the shell 6, therefore with an inverted conicity relative to that of the internal passage 23 The sleeve 22, which is surrounded by the half-shells 21a and 21b whose shape corresponds to that of the external lateral surface of the

  cuff 22 against which they are applied,

  cit so gradually from its end adjacent to the shell 6 to its end facing the fastener

puffed 15.

  The half-shells 21a and 21b and the internal reinforcement sleeve 22 of the blade root 4 are surrounded and secured to a bearing for mounting and rotating the blade root on a hub, which bearing is constituted by a sleeve 24 control of the pitch of the blade This sleeve 24, not shown in Figure 9 but visible in Figures 1,

  2 and 8, has a substantially truncated general shape

  that with a large base facing the shell 6, at its inner and outer side surfaces The taper of its

  central passage corresponds substantially to that of the

  shells 21a and 21b and the outer surface of the

  internal reinforcing cuff 22 to allow its

  In conjunction with a collective pitch control device of the blades of a variable pitch multi-blade hub comprising a plurality of blades such as the blade 1, the sleeve 24 has, radially outwardly projecting, a control lever of not 25 This lever 25 is pierced by an opening 26 for the accommodation of a link ball joint to the collective control device of the pitch, in a manner described in the aforementioned joint application, as well as in the aforementioned French patents, which will be referred to for more details on this assembly and the structure

  collective pitch control device.

  This sleeve 24 may be a metal sleeve, as described with reference to FIG. 14 of patent FR-2,616,409

  above, and its arrangement may correspond to the representation

  FIG. 16 of the same patent, the metal sleeve 24 then being attached by gluing or hooping on the foot of the assembled blade. In known manner, the shrink fitting is provided by heating the sleeve 24,

  wrapping it on the blade root and then cooling it.

  However, in a preferred embodiment which provides a saving in mass, the sleeve 24, like the internal reinforcement sleeve 22, is an injection-molded part made of a composite of short reinforcing carbon fibers, embedded in the matrix. PEEK, which is responsible

  about 30% by weight of the reinforcing fibers.

  Finally, the sleeve 24 is integral and surrounded, at each of its axial ends, with a ring 27 or 28, made of metal or ceramic, which constitutes a rotational range of the sleeve 24 on the hub, these rings 27 and 28 being secured to the sleeve 24 by gluing or hooping. The blade 1 is thus such that all its components, with the exception of the rings 27 and 28 and, optionally, the sleeve 24, are made of PEEK / carbon composite, the assembly of the various components and the cohesion of the

  blade being provided by PEEK resin.

  A variant of this blade is represented on the

  FIG. 10 The blade 31 according to this variant differs substantially only

  4 of the structure of its root portion 35, which is no longer provided with a laminated fastener, but with a root portion 35 with a connecting loop. spar 37 also consists of a skein of continuous and unidirectional carbon reinforcing fibers, agglomerated by the PEEK resin, and which has two parts parallel to each other and contiguous to each other, along of the longitudinal axis of the blade 31, to form two beams of spar joined and received in the shell 36 in the current or profiled part 32 of the blade 31 These two beams of the spar 37 are connected to one another by a a substantially flattened loop portion, which constitutes the root part itself, and whose outer end to the shell 36 is looped in a loop 38 and forms a hub-and-loop connection fastener (not shown) to surround a bushing by which the blade 31 is destined The loop fastener 38 is connected to the two beams of the spar 37 received in the shell 36 by two skein portions forming two sections. twisted fastening bundles 37 a and 37 b of the root portion 35 For the rest of the structure of this blade 31, there is found in the shell 36 a front filler body (not shown) and a rear filler 40 which are pultruded profiles in PEEK / carbon composite with long and unidirectional fibers, the shell 36 is made as the shell 6 of the blade 1, the blade root 34, shown in the figure without the pitch control sleeve and its rings of rotation, also comprises laminated half-shells 41a and 41b extending the intrados and extrados laminate coatings of the shell 36, with at least one additional layer of reinforcing fabric t PEEK / carbon, and an internal reinforcement cuff 42, injection molded into

  PEEK / carbon composite with short reinforcing fibers.

  The manufacturing method of the blade of FIGS. 1 to 9 comprises an essential step of assembling by fusion pressure of the PEEK / carbon composite components of the blade, after these components have been prefabricated under

the shape of elementary pieces.

  To make each lining of the intrados or extrados 6a or 6b in the form of a prefabricated elementary piece made of PEEK / carbon composite, it is first possible to make a plate 50 (see FIG. rectangular flat layers in the semi-rigid state of carbon fibers agglomerated with PEEK resin, that the coatings 6a and 6b comprise layers, and of the same nature, that is to say, for the example considered, two layers of continuous and unidirectional carbon fiber sheets, oriented along the width of the plate 50, the direction of which corresponds to the longitudinal direction or span of the shell 6, and which is greater than twice the span of this shell 6, and at least one upper layer of carbon fiber fabric agglomerated with the PEEK resin and whose directions of the weft and warp threads are inclined at 450 relative to

  to the width of the plate 50 The stack also includes

  at least one reinforcing strip 51, also in the semi-rigid state, of carbon fiber fabric agglomerated with PEEK resin but whose directions of the warp and weft threads are oriented one according to the width and the other according to the length of the plate 50, this band or strips 51 extending longitudinally through the central portion of the plate 50, which central portion is intended to form the extensions in half-shells

  21a and 21b of the coverings 6a and 6b of the shell 6.

  The stack of these layers and strips is heated to a melting temperature of the PEEK matrix, of the order of 4000 C, and put under a low pressure, of the order of 0.1 to 0.5 M Pa, in a compacting mold, to ensure the connection between the different layers and fiber strips by the PEEK matrix Then the stack is cooled and the PEEK resin is obtained by solidification of a plate 50

  precompacted, PEEK composite / carbon in the sensitive state-

  stiffness, in which then cut, by jet of

  fluid, panels such as 52a and 52b, arranged

  end to end according to the width of the plate 50, and facing each other by the extensions intended to form the half-shells 21a and 21b of the blade root, and each of these panels 52a and 52 b having the flat developed form respectively of the intrados coating 6 a

and extrados 6 b.

  Each flat panel 52a or 52b is then shaped

  to the desired shape of the intrados 6a or extra-

  back 6 b corresponding by stamping in a stamping mold. Embossing is a known method of transformation used for composites with thermoplastic matrix and with long or continuous reinforcing fibers, and makes it possible to obtain very high production rates from the cutting, if necessary, of the blank to be stamped in a machine. plate, web or strip of larger dimension of the thermoplastic composite, this method consists in heating the blank, for example at infra-red or by passing through a forced hot air tunnel furnace, then to transfer the preheated blank to a temperature sufficient to soften or melt the matrix on a press comprising punching tools, on the one hand, and, on the other hand, die, then to close the press with a cooling time of

  a few tens of seconds to allow solidification

  matrix after shaping the blank between punch and die, then finally to unmould and possibly to

  deburr the piece thus shaped.

  This embossing process is carried out as shown schematically in FIGS. 12 and 13, in a stamping mold having a lower mold portion 53a, forming a die, and an upper mold portion 53b, forming a punch, which each have respectively one of two complementary indentations 54a and 54b corresponding to the inner and outer shapes of the laminate coating 6a or

  6b that stamping mold 53 can achieve.

  By way of example, the stamping mold 53 of FIGS. 12 and 13 makes it possible to shape the lower surface coverings 6a. The cavity 54a internal to the lower mold portion 53a thus corresponds to the external shape of the 6, while the cavity 54b internal to the upper mold part 53b corresponds to the internal shape of the same intrados coating 6a In FIG. 12, between the two mold parts 53a and 53 b spaced from each other, and each maintained at a temperature below the melting temperature of the PEEK matrix, for example of the order of 1500 C, the flat panel 52 a having the same structure that the intrados coating 6 has but the shape of the latter as developed flat This panel 52a is disposed in the mold 53 after preheating

  at a temperature of the order of 400 C, then the two half

  The molds 53a and 53b are closed, as shown in FIG. 13, in order to shape the desired profile of the intrados coating 6a. After cooling in the closed mold 53, the PEEK matrix becomes solid, the mold 53 is open and the intrados coating 6a can be demolded, as shown in Figures 14 and 15 The sections of Figures 17 and 18 show the evolution of twisting of the intrados coating 6a in the current portion 2 of the blade , and the section of Figure 16 shows the half-shell

  21 formed in the axial extension of the inner coating of

back 6 a.

  The upper surface layer 6b is made in the same way by stamping a panel 52b in a stamping mold similar to the mold 53, and whose indentations of the two mold parts respectively correspond to the external shape and the internal form of this coating

extrados 6 b.

  The elementary part constituting the internal reinforcing cuff 22 made of PEEK / carbon composite is produced

by injection molding.

  It is known that injection molding is a molding method in which a part or all of the molding material is introduced in fluid form, via a pressure device, into a previously closed mold. achieve, at high rates, pieces of geometric shapes very

  varied with a good respect of dimensional tolerances.

  It is known to produce fiber reinforced thermoplastic parts by injection from a semi-finished product.

  in the form of powder or granules on a specific machine

  What is known as the injection molding machine It is also known that the production cycle comprises five main stages: namely, the plasticization of the material, the closure of the

  mold, filling the mold under pressure, cooling it

  The closing of the press is ensured, for example, by hydraulic cylinders or mechanical systems, with a closing force which can be very high. The plasticization of the material and the feeding of the mold take place by means of an injection unit, which comprises a metering system, a screw-sleeve assembly and a hydraulic cylinder The rotating screw drives the material delivered by the metering system, so that the material heats up both by friction and by contact with the sheath, which comprises a heating device The fluidized material by heating is then injected into the mold, by a translational movement of the screw, which functions as a piston, this translational movement being ensured by a cylinder of the injection unit The cooling of the mold is then carried out either naturally, after stopping the heating, or by circulation of a fluid (water, oil) d in the mold The mold is then obtained, after opening the mold, and may include an ejection phase, which is carried out

  automatically by means of mechanical or pneumatic ejectors

  c. All these devices being known, the injection molding tooling of the sleeve 22 will not be further described herein because it has no originality, given the simple geometry of the sleeve 22 (tubular part with generally frustoconical internal and external lateral surfaces, which can easily be molded in one piece or in two halves). It is however indicated that the sleeve 22 is injection-molded with a composite material based on PEEK matrix granules in which short fibers of

  These granules of thermoplastic PEEK / car-

  bone are semi-products available, for example, under the commercial references 150 CA 30 or 450 CA 30 from the British company ICI or its subsidiaries It is pellets 2 to 4 mm in length and 1 to 3 mm in diameter, PEEK resin loaded to approximately 30% by mass of carbon in

  short fibers contained in the dry state in PEEK resin.

  Before use, these granules are parboiled at a

  temperature of about 150 C for at least three hours.

  Then these granules are heated to a melting temperature of the PEEK matrix, of the order of 4000 C, and the composite material fluidized by melting its matrix is then injected into the mold, maintained at a temperature between about 1500 C and approximately 2000 ° C., but preferably close to 150 ° C. After cooling and solidification of the PEEK resin, the sleeve 22 can be demolded. The mechanical characteristics of the hot injectable composite material thus constituted are very satisfactory, since under conditions of use at ambient temperature of 230 ° C., for example, the modulus of YOUNG in tension is 24000 M Pa, and the tensile strength in static tension close to 200 M Pa. It is noted that these values are of the same order of magnitude as those of a balanced glass fabric, that is to say the same percentage of fibers in the warp and weft directions, for example a type E glass cloth with a mass of fibers, don the YOUNG modulus and the static tensile strength are respectively of the order of 20000 M Pa and 300 M Pa. The PEEK / carbon composite material resulting from the hot injection from the

  The granules described above therefore have characteristics

  remarkable for an injected material.

  These granules contain 24% by volume of fibers and 76% by volume of PEEK resin, and their density is of the order of 1.41 to 1.44 kg / dm 3. The PEEK matrix itself has a resistance. tensile strength of the order of 90 to M Pa, an elongation at break of 70%, a YOUNG modulus of the order of 4000 M Pa, a glass transition temperature of 1430 C and a melting temperature of 3900 C The

  reinforcing fibers are high-strength carbon fibers

  "XAS" trade name of the British company COURTAULDS, of a length in the range of 0.1 to about 0.5 mm The PEEK / carbon thermoplastic composite

  injectable thus obtained has very good characteristics

  mechanical problems, good thermal behavior and

  no sensitivity to accelerated wet aging.

  When the pitch control sleeve 24 is not a metal sleeve but a composite component

  thermoplastic PEEK / carbon blade, the elemen-

  its constituent is made, like the sleeve 22, by injection molding, in a mold (not shown because of very simple shape since corresponding to the frustoconical shape of the sleeve 24) heated to a temperature of the order of 1500 C, of a composite material with short carbon fibers embedded in a molten PEEK matrix, obtained by heating at a temperature of about 4000 C of the granules

as described above.

  The elementary part constituting each of the front 9 and rear 10 PEEK / carbon composite filling bodies of the blade 1 is produced by pultrusion of a profile of

  continuous and unidirectional carbon fibers

glomerated with PEEK resin.

  It is known that pultrusion is a process of

  This process is well adapted to the production of the front and rear filler bodies 9 and is therefore suitable for producing solid or hollow sections of constant section.

  of the blade 1 since the rope of the latter is sensi-

  This process essentially consists in drawing continuous reinforcing fibers, in the form of carbon rovings, through a resin impregnation tank, then a heated die, in which the profiling is formed by compacting the profile. These pultruded profiles may have high levels, of the order of 40 to 60%, of reinforcing fibers in volume, and

  therefore good mechanical performance in the long-term

  dinal Pultrusion also makes it possible to continuously mold laminate profiles, the profiles being made by drawing impregnated fiber plies through a die. During the passage in the heated die, the plies are compacted and form, at the outlet, a profile. Precise dimensions and a good surface appearance This process allows to realize solid profiles in

  PEEK resin and continuous fiber reinforcement and unidirectional

  The pultrusion line which makes it possible to produce these profiles is conventional, and is therefore not described in detail. It is sufficient to recall below that consists of four basic elements namely the creel, the impregnation device, the die and the traction system The creel is the upstream part of the pultrusion line and is intended to gather all the bits or fibers necessary for reinforcing the profile by ensuring a perfect distribution of the fibers to the impregnating device The latter generally comprises a resin tank in which the impregnation is generally performed by dipping At the outlet of the tray, the impregnated fibers are directed towards the die, which exerts compaction of the impregnated sheets, and at the exit of which the PEEK resin is sufficiently cooled and solidified to maintain its shape to the profile. Tif traction, located at the exit of the die, can be of a type called "caterpillar" or "AC clamping", and stretches the entire profile and fiber sheets with good accuracy of speed This process makes it possible to produce profiles having a fiber equilibrium, an optimization of the fiber content, for example at 60% by volume, an excellent accuracy of the dimensions, which can be less than one-tenth of a millimeter, the sections being manufactured continuously while guaranteeing a quality These pultruded profiles, of excellent dimensional stability, have a remarkable rigidity and good absorption of vibration when subjected to fatigue forces. These pultruded sections are therefore suitable for use as filler in blades highly mechanically and thermally stressed for long service life. The composite PEEK / carbon composite part, which is the spar 7 with integrated root part 5

  with a laminated fastener 15, is made in the following manner.

  A plate 55 (see FIG. 19) is first made by stacking, for example, sixteen rectangular layers in the state.

  rigid web of continuous and unidirectional carbon fibers agglomerated with PEEK resin, the webs being crossed

  layer to another in the stack so

  that the fiber orientation of a layer is

  to the fibers of the adjacent layer or layers in the stack, and that the fiber orientations of the different plies are substantially 450 relative to the direction of the length or width of the plate 55. stacking in a compaction autoclave, wherein the stack is heated to a temperature of about 4000 C to melt the PEEK resin, and is subjected to a pressure of the order of 0.1 to about 0, 5 M Pa, exerted by a press in the autoclave or by the technique of "vacuum bag", that is to say that the stack is disposed in a tight bladder of a polyimide film, for example UPILEX S, which supports the melting temperature of the PEEK matrix, this bladder being connected to a source of depression, which

  allows a relative vacuum in the bladder to

  Then, after cooling and solidification of the PEEK resin, which solidarises all the

  layers of the stack, a precompact plate 55 is obtained.

  wherein laminated elements 56, each of which has a shape and a structure enabling it to form the lower laminated element 15a or greater 15b of the laminated fastener 15, are cut by fluid jet while two laminated elements 56 superimposed are necessary to constitute the interlayer laminate element 15 c of this

laminated fastener 15.

  Alternatively, the plate 55 may be formed by compacting nine layers of carbon fiber fabric agglomerated with the PEEK resin and whose directions of the weft and warp threads are inclined at 450 per second.

  relative to the width or length of the plate 55.

  The side-filling laminated elements 18a and 18b of the laminated fastener 15 are also cut by jet of fluid in the plate 55, or, if necessary, in another similar precompacted plate of thickness

appropriate.

  The spar 7 itself consists essentially of two blades made by continuous and unidirectional carbon fiber pultrusion agglomerated by the PEEK resin. Each blade is a pultruded profile, manufactured in the same way as the front and rear filler bodies 10, by the known method and using a known device as mentioned above, from ribbons or sheets of continuous, unidirectional and longitudinal carbon fibers agglomerated with PEEK resin, by passing through a spinneret carried to a temperature of about 400 ° C to melt the PEEK matrix Each of the two identical pultruded blades 57a and 57b of the spar 7 is for example constituted of a pultruded section of sixteen plies of such fibers As shown in FIG. pultruded blades 57a and 57b are arranged in a mold 60 for compacting the spar 7 which comprises a lower part of the mold 60a and a mold top

  b each having an internal imprint that respects

  the shape of the lower part and the upper part of the spar 7 manufactured, except at the level of

  the laminated fastener 15, for which the imprint cor-

  The two blades 57a and 57b are superimposed, along the part of their length which must be received in the shell 6 of the blade, with the interposition between them of three layers. 58, in the semi-rigid state, of continuous and unidirectional carbon fibers, oriented

  longitudinally, and agglomerated with PEEK resin.

  In order to keep away from one another the parts of the length of the two blades 57a and 57b which are to constitute the torsionable blades 13a and 13b of the root portion 5, a wedge shaped tool steel 59 is interposed between these portions of the blades 57a and 57b Then each of the end portions of these parts separated from the blades 57a and 57b, which end portion is intended to form the connecting end portion 14 a or 14b of the corresponding torsionable blade 13a or 13b is sandwiched between two prefabricated laminated elements 56, as cut in the precompacted plate 55 of FIG. 19. The two laminated elements 56 thus directly superimposed on one another. the other, between the end portions of the parts

  spaced apart from the two blades 57a and 57b are arranged directly

  behind the steel wedge 59, on whose faces an aerosol mold release, for example of the type known as

  denomination "FREKOTE", is vaporized before setting up.

  This demoulding layer has the effect of facilitating the removal of the removable tool formed by the steel wedge 59 after compaction of the spar This compaction is ensured by closing the mold, as shown in FIG. 21, while all the composite elements contained in the mold are heated to a temperature of about 400 ° C to ensure the melting of the PEEK matrix, and that these components are simultaneously subjected to pressure

  of the order of 0.6 M Pa The three layers of unidirectional fibers

  58, which are arranged opposite the end of the removable wedge 59, and which are integrated in the spar 7 by the compacting operation, have the role of avoiding any deformation in thickness of the blades 57 a and 57 b of the spar, at the end of the metal wedge 59, because this end can be of strictly zero thickness Thus, the PEEK matrix ensures the joining of the four laminated elements 56 at the ends of the parts separated from the two blades 57 a and 57 b of the spar, and the joining of the two laminated elements 56 directly superimposed to form the interlayer laminate 15 c of the laminated fastener 15, and also the joining together of the superimposed portions of the two blades 57 a and 57 b and three interlayers of fibers 58 After cooling and solidification of the PEEK resin, the mold 60 is open and the spar 7 compacted and made of a the piece is demolded and has the structure shown in the figures

  22 and 23 and as already described above.

  In particular, each of the two pultruded blades 57a and 57b of the spar 7 constitutes, on the one hand, a beam of spar received in the shell 6 and integral with the corresponding beam of the other blade, and, on the other hand, a blade attachment beam 13a or 13b, connected to the other by its connecting end portion 14a or 14b via the fastener

common puff pastry 15.

  Since all the PEEK / carbon thermoplastic composite components of the blade 1 have been made in the form of prefabricated elementary parts, these components, with the exception of the pitch control sleeve 24, are arranged in a submerged assembly mold. blade pressure, schematically shown in Figure 27, the mold 61 comprising a lower mold portion 61a and an upper mold portion 61b which have complementary internal impressions having, respectively, the shape of the lower section and the extrados part of the blade, the prefabricated elementary parts being arranged in this mold so that they occupy in the latter the respective positions they occupy in the blade 1 This operation consists essentially in first arranging the coating 6a in the lower mold portion 61a, then to be placed on the intrados coating 6a before the 9th filling bodies t rear 10 on either side of the spar 7, with the establishment of the internal reinforcing cuff 22, in one piece or in two complementary parts, around the root portion 5, which,

  with the laminated fastener 15, are preferably positioned

  born in this mold by a positioning tool that surrounds them and in particular fills the internal passage 23 of the

  cuff 22, around the blades 13a and 13b which passes through it.

  The prefabricated elementary pieces thus arranged are heated to a temperature of the order of 400.degree. C., to melt the PEEK matrix, and the mold 61 is closed to

  exercise sufficient pressure on these parts to ensure

  the continuity of the PEEK matrix between the different parts and their assembly by melting under pressure, in a single operation, a suitable pressure may be of the order of 1 M Pa The cooling of the mold and its contents then ensures the solidification of the PEEK matrix and the stiffening of all the elementary parts thus assembled, and the blade thus obtained can then be

  demoulded by opening the mold To finish the production

  tion of the blade, the metal or ceramic rings 27 and 28 are attached by gluing or shrinking on the sleeve 24, and the latter, if it is metallic, is itself then attached by gluing or hooping around the half-shells 21 a and 21b and the internal reinforcement cuff 22 of the foot

of blade 4.

  If the sleeve 24 is itself a thermoplastic PEEK / carbon composite injection molded part, it can

  possibly be assembled to the other components in

  PEEK / carbon position of the blade during the molding operation, subject to arrange mold footprints accordingly. Similarly, the protective cap of the leading edge, titanium or stainless steel for example, can be reported by gluing on the blade after demolding, or secured to the blade during molding, at the same time as the assembly of all the composite elements of the blade, if the impressions of the mold are arranged accordingly and that the cap is placed in the mold before closing in the appropriate position relative to the other elements it contains. The manufacturing method of the blade variant shown in FIG. 10 differs from that just described in the step of producing the prefabricated elementary piece intended to constitute the spar 37 having a root portion 35 to Loop link fastener 38 Such a spar 37 can be made according to the method described with reference to FIG. 9 of the French patent

  2,616,409 cited above which is applied to other materials.

  According to this method, this elementary piece is made by winding a ribbon of continuous carbon fibers, unidirectional and longitudinal agglomerated by PEEK resin, in several layers and under mechanical tension around two coils, parallel axes but spaced l The mechanical tension at winding can be obtained by subjecting one of the two coils to a pull which tends to move it away from the other at the same time. during the winding of the ribbon A skein wound in an elongated and closed loop is thus obtained, which is shaped by compacting under pressure and at a melting temperature of the PEEK matrix, of the order of 4000 C, in a mold having a core to keep apart the two parts of the skein intended to constitute the two fastening beams 37 a and 37 b connected

  to one another by the looped end 38 of the spar 37.

  After solidification of the PEEK matrix by cooling

  of the compacting mold and its contents, the

  of the winding on the side opposite the loop fastener 38 is cut, to reduce the length of the spar 37 thus obtained to the desired length according to the span of

the blade.

  The spar 37 thus produced in the form of a prefabricated elementary piece is then put in place with the other prefabricated components made of PEEK / carbon composite of the blade in a final assembly mold by fusion under pressure, as described above for the blade of the In this example also, the rings of the blade root, and possibly the pitch control sleeve are mounted on the blade by gluing or hooping, after

the molding of the latter.

  Another advantage of the blade and the method of the invention is that the molding of a thermoplastic is obtained without soiling the mold It is therefore not necessary to deposit a layer of adhesive in the mold to obtain a "finished" state blade coatings, as is the case when molding thermosetting composite blades

of the state of the art.

Claims (23)

  1 Blade essentially of composite material, for a rotorcraft rotor, and comprising: a composite rigid shell (6, 36), with an aerodynamic profile, elongated longitudinally along the span of the blade (1, 31) and a longitudinal end thereof, to be turned towards a hub of the rotor, has a blade root (4, 34), said shell (6, 36) comprising at least one layer of reinforcing fibers bonded by a matrix of a synthetic stiffening resin, at least one spar (7, 37) of which at least a portion is housed substantially longitudinally in the shell (6, 36), and comprising at least one composite beam   elongated, continuous and unidirectional reinforcing fibers   agglomerated by a matrix of a synthetic stiffening resin, and at least one filling body (9, 10; 40) disposed in the shell (6, 36) between the latter and at least one spar (7, 37), and also comprising reinforcing fibers agglomerated by a matrix of a synthetic stiffening resin, characterized in that the resin of the matrixes of the shell (6, 36), of each filling body (9, 10; 40) and of each bundle each spar (7, 37) is a thermoplastic resin, ensuring the assembly and cohesion between them of the shell (6, 36), of the part of each spar (7, 37) housed in the shell (6, 36). ), and each body of filling (9, 10; 40).   2 blade according to claim 1, characterized in that   that the thermoplastic resin is a poly-ether-resin   ether-ketone (PEEK) and the reinforcing fibers are chosen   among the carbon and glass fibers.   3 blade according to claim 2, characterized in that the reinforcing fibers of the shell (6, 36), each composite filler body (9, 10; 40) and each composite beam of each spar (7, 37). are likewise   nature, and are preferably carbon.   4 blade according to one of claims 1 to 3,   characterized in that each filler body (9, 10;) of the blade (1, 31) is composite and consists of continuous and substantially unidirectional reinforcing fibers   agglomerated by said thermoplastic resin.   Blade according to claim 4, characterized in that each filler body (9, 10; 40) is a profile pultruded from said continuous and unidirectional fibers and of said thermoplastic resin.   6 blade according to one of claims 1 to 5, of which   the shell (6, 36) has extrados (6b) and intrados (6a) strafed surfaces extending from the leading edge (8) to the trailing edge (11) of the blade (1, 31), characterized in that each layered layer (60, 66) comprises a plurality of superposed layers of reinforcing fibers, each layer of which is a fiber fabric or a web of continuous fibers and   unidirectional, agglomerated by the thermoplastic resin   than. 7 blade according to claim 6, characterized in that each laminate coating (60, 66) comprises, from the inside to the outside of the shell (6), two layers of long and unidirectional fiber layers, oriented substantially along the longitudinal axis of the blade (1), and covered with at least one layer of fiber fabric, the directions of the weft and warp threads are oriented substantially at 450 relative to the longitudinal axis (A) of the blade (1).   8 blade according to one of claims 6 and 7, of which   the blade root (4, 34) is tubular and extends the shell (6, 36) substantially axially, characterized in that the tubular blade root (4, 34) is, at least partly, consisting of two half-shells 21a, 21b, 41a, 41b), each of which consists of an extension of one respectively of the two laminate coatings (6a, 6b). 9. Blade according to claim 8, characterized in that each laminated coating (6 a, 6 b) is reinforced, at said corresponding extension, by at least one additional layer (51) of fiber fabric, one of the directions warp and weft threads is sensitive-   oriented along the longitudinal axis (A) of the blade (1).   Blade according to one of Claims 1 to 9,   characterized in that at least one elongated composite bundle of at least one spar (7, 37) consists of at least one blade formed by agglomeration by the resin and side-by-side or superimposed of several layers of   continuous and unidirectional fibers oriented sensitive-   along the longitudinal axis of the blade (1, 31), said blade not being twisted in the shell (1, 31) according to the span, and about said longitudinal axis (A) of the blade, and having a substantially rectangular cross section, at least in its portion adjacent to the foot of   blade (4, 34) and internal to the shell (6, 36).   11 blade according to claim 10, characterized in that said blade has a cruciform cross section, over part of its length internal to the hull   (6, 36) and adjacent to the blade tip (3).   12 blade according to one of claims 10 and 11,   characterized in that said non-twisted blade is surrounded by the shell (6, 36) and the filling body (9,; 40) which are twisted around the longitudinal axis (A) of pitch change of the blade (1, 31) located about% on the rope from the leading edge (8) of the blade (1, 31).   13 blade according to one of claims 1 to 12, for   multi-blade rotor, with blades that can be dismounted individually, suitable for use as a tail rotor, in particular a ducted rotor, helicopter, and of the type comprising a root part (5, 35) of blade (1, 31) comprising at least one bundle of attachment (13 a, 13 b, 37 a, 37 b) of blade which is   elongate, composite, and twistable around its long axis   longitudinal, and extending, outside the shell (6, 36) through the tubular blade root (4, 34) at least one composite beam of at least one spar (7, 37) of longitudinal axis substantially parallel to that (A) of the blade (1, 31), the end of each attachment beam (13 a, 13 b; 37 a, 37 b), on the opposite side to the hull (6, 36) , being arranged as a linkage attachment to a rotor hub, characterized in that each attachment beam (13a, 13b; 37a, 37b) of the root part (5, 35) is of one single piece with the composite beam of the spar (7, 37), and consisting of   the same reinforcing fibers agglomerated with the same heat resin   moplastique. 14. Blade according to claim 13, characterized in that at least one spar (37) consists of a skein of continuous and unidirectional reinforcing fibers, agglomerated by said thermoplastic resin, and which has two parts substantially parallel to each other. other and to the longitudinal axis of the blade, which constitute two beams of spar (37) received in the shell (6), and connected to each other by a substantially flattened loop portion, which constitutes the part root end (35), the looped end of which forms a loop connection (38) for connection to the hub, to surround a bushing through which the blade (31) is intended to be individually removably attached to the hub by a bolt, said loop fastener being connected to said beam beams (37) received in the shell (36) by two skein portions forming two torsionary tie beams (37 a,   37 b) of the root portion (35).   Blade according to Claim 13, characterized in that the hub connection clip of at least one fastening beam (13a, 13b) is a laminated fastener (15), comprising at least two laminated elements (15). a, 15b, 15c) between which a connecting end portion (14a, 14b) of the fastening beam (13a, 13b), on the opposite side to the shell (6), is taken sandwiched and secured, each laminated element (15a, 15b, 15c) comprising a stack of at least two layers of the same reinforcing fibers as those of the attachment beam (13a, 13b), agglomerated by said resin thermoplastic, which secures said laminated elements (15a, 15b, 15c) to said connecting end portion (14a, 14b), the laminated fastener (15) being shaped to abut towards the hull (6), against removable means for retaining the laminated fastener (15) and the blade (1) at the hub.   Blade according to Claim 15, characterized in that each fastening bundle (13 a, 13 b) comprises at least one pultruded blade (57 a, 57 b) of continuous and unidirectional fibers in said thermoplastic resin, said fibers being oriented substantially along the longitudinal axis of the fastening bundle (13a, 13b), and each laminated element (15a, 15b, 15c) of the laminated fastener (15) comprises a stack of several layers of cross sheets of continuous and unidirectional fibers and / or layers of fiber fabrics, so that the directions of the fibers are substantially at 450 relative to the axis   longitudinal beam of attachment (13 a, 13 b).   Pale blade according to one of Claims 15 and 16,   characterized in that its root portion (5) comprises at least two torsionous bundles (13a, 13b) which progressively separate from one another in the direction of a common laminated fastener (15), and from a single beam of spar (7) housed in the shell (6), each of the torsion beams (13 a, 13 b) consisting of a part of the length of one respectively of several blades   pultruded (57 a, 57 b) continuous fibers and unidirectional   agglomerated by said thermoplastic resin, which are applied against each other over the remainder of their length, with interposition of at least one web (58) of the same continuous and unidirectional reinforcing fibers, having the same orientation along the axis of the blade (1), and agglomerated by the same resin, between two adjacent blades (57 a, 57 b), to form the spar portion (7) housed in the hull (6).   Blade according to one of Claims 13 to 17,   for multi-blade rotor whose blades are moreover variable pitch, and of the type of which the blade root (4) comprises a bearing for embedding and rotation of the blade root on a hub, said bearing comprising a sleeve (24). ) blade root which comprises, projecting radially outwardly, a lever (25) for controlling the pitch, intended to be articulated to a collective control device of the pitch of the blades (1) of the rotor, characterized in that the sleeve (24) is a molded tubular sleeve made of a composite of short reinforcing fibers,   glass or carbon, embedded in the same thermoplastic matrix   the other composite components of the blade (1), this sleeve (24) having, on at least a part of its length, a generally frustoconical internal and external shape   with a large base facing the shell (6).   19 blade according to claim 18, characterized in that the sleeve (24) is integrally surrounded, at each of its axial end portions, by one respectively two rings (27, 28) metal or ceramic, forming rotational bearings of the sleeve (24) on the hub.   Blade according to one of claims 18 and 19,   characterized in that the blade root (4) also comprises   an inner reinforcing cuff (22), also molded from a composite of short reinforcing fibers, made of glass or carbon, embedded in the same thermoplastic resin, the central passage of said cuff (22), traversed by the root part ( 5) of the blade (1), being of shape   frustoconical small base turned towards the shell (6).   21 Method of manufacturing a blade according to one   Claims 1 to 20, including the composite shell (6, 36)   consists of a lining (6a) and an extrados lining (6b) laminated, characterized in that it comprises the following steps, consisting of: producing each of the thermoplastic composite components of the blade (1, 31) in the form of a prefabricated elementary part, arranging the prefabricated elementary parts in a pressurized heating assembly mold (61), comprising a lower mold part (61 a) and a part of upper mold (61b) having complementary internal impressions, respectively having the shape of the intrados portion and the extrados portion of the blade (1, 31), so that said prefabricated elementary pieces occupy the mold ( 61) the respective positions they occupy in the blade (1, 31), to close the mold (61) and to heat said parts to a temperature sufficient to melt the thermoplastic matrix, under a sufficient pressure p to ensure the continuity of the thermoplastic matrix between said parts and their assembly by fusion under pressure, to cool the mold (61), to ensure the   solidification of the thermoplastic matrix and stiffening   cation of all the basic parts as well as   it is possible to demold the blade (1, 31) thus obtained and to bring rings (27, 28), by gluing or by hooping, around a sleeve (24) of blade root, itself reported, by bonding or hooping, around said blade root (4, 34) if it is not made of a thermoplastic composite and already   assembled by pressure fusion to the other elemen-   prefabricated parts of the blade (1, 31).   Method according to claim 21, characterized in that it further comprises the step of producing the elementary part constituting each filler body (9, 10; 40) by pultrusion of a profile of continuous and unidirectional fibers, of carbon preference, agglomerates   in a thermoplastic matrix, preferably PEEK.   Method according to one of claims 21 and 22,   characterized in that it comprises more the step of producing the elementary piece constituting a laminate coating of intrados (6a) or extrados (6b) of the shell (6) by shaping by stamping, between two portions (53a, 53b) of mold (53) maintained at a temperature below the melting temperature of the matrix, and having complementary indentations (54a, 54b) corresponding to the shape of the laminate coating considered (6 a, 6 b), a panel (52 a) preheated to a matrix melting temperature, having the flat expanded form of the considered laminate coating (6 a, 6 b), and cut into a precompacted plate (50 ), obtained by stacking several layers   of continuous and unidirectional fibers and / or   of reinforcement agglomerated by the matrix, under pressure and at a melting temperature of the matrix, then rigidification in plate by solidification of the matrix by cooling.   Method according to one of claims 21 to 23,   for manufacturing a blade (1), whose blade root (4) is equipped with a pitch control sleeve (24), also made of a thermoplastic matrix composite, characterized in that it further comprises the step of performing the elementary part constituting the sleeve (24) by molding by   injection, in a mold heated to a temperature   lower than the melting temperature of the matrix, a composite material consisting of short reinforcing fibers,   preferably carbon, embedded in a thermal matrix   molten moplastic, preferably a PEEK matrix.   Method according to one of claims 21 to 24,   for manufacturing a blade (1), whose tubular blade root (4) is reinforced by an internal reinforcing cuff (22),   also in thermoplastic matrix composite, which is   characterized in that it further comprises the step of providing the elementary part constituting the sleeve (22) by injection molding, in a mold heated to a temperature below the melting temperature of the matrix, of a material composite consisting of short reinforcing fibers, preferably carbon, embedded in a molten thermoplastic matrix, preferably a PEEK matrix.   Method according to one of claims 24 and 25,   characterized in that said reinforcing short fiber composite material embedded in a molten thermoplastic matrix is obtained by heating until melting of said matrix, granules of short fibers contained in the dry state in said matrix, which is loaded at approximately 30% by mass of the short fibers, the heating of the granules being preferably carried out after steaming of the granules at a temperature of the order of 150.degree. at least three hours.   Method according to one of claims 21 to 26,   for manufacturing a blade (31), having at least one spar (37) of thermoplastic composite, of which an outer portion to the shell (36) constitutes a root portion (35) with two attachment beams (37 a , 37 b) forming a loop fastener (38) for connection to the hub and extending at least one beam of spar (37) housed in the shell (36), characterized in that it further comprises the step of realizing the elementary piece constituting said spar   (37) by winding a ribbon of reinforcing fibers   continuous and unidirectional bonded by said thermoplastic matrix, in several layers and under mechanical tension around two coils, then by shaping in a mold by compacting the winding under pressure and at a matrix melting temperature, followed by a cooling solidification of the matrix, and a cutout of an end portion of the winding of the side   opposite the loop fastener (38).   Method according to one of claims 21 to 26,   for manufacturing a blade (1) having at least one spar (7) of thermoplastic composite, a part of which is external to the shell (6) constitutes a root portion (5) of blade to at least one attachment beam (13) a, 13b), of which a hub connection end portion (14a, 14b) is provided with a   laminated fastener (15), also of thermoplastic composite   and extending a beam of spar (7) housed in the shell (6), characterized in that it further comprises the step of making the elementary piece constituting the spar (7) by making each beam of fastener (13a, 13b) and the beam spar (7) that it extends in the form of a blade (57a, 57b) of continuous and unidirectional reinforcing fibers agglomerated by said thermoplastic matrix, obtained by pultrusion at a melting point of the matrix, of several plies of continuous and unidirectional fibers agglomerated by this matrix, and, if said root portion comprises at least two attachment clusters (13 a, 13 b), each of which extends respectively a beam of spar (7), to superpose portions of the blades (57 a, 57 b) corresponding to form the spar portion (7) housed in the shell (6), with interposition of at least one layer ( 58) continuous and unidirectional fibers s agglomerated by said matrix between overlapping portions of adjacent blades (57a, 57b), and to implement a wedge-shaped removable tooling (59) between portions to be spaced apart from each other two neighboring blades (57 a, 57 b) to form two fastening bundles (13 a, 13 b) of the root portion (5) and then disposing the blade (s) (57 a, 57 b) in a mold (60), and interposing each connecting end portion (14a, 14b) of a pultruded blade (57a, 57b) between two laminated elements (56) of the fastener (15) , so as to superimpose all the laminated elements (56) of said fastener (15), to close the mold (60) and to compact its contents under pressure and at a melting temperature of said thermoplastic matrix, to then solidify the matrix by cooling to stiffen the spar (7) thus obtained with the laminated fastener secured to its root part (5).   The method according to claim 28, characterized in that it further consists in producing each laminated element (56) of the thermoplastic composite laminated fastener (15) by stacking several layers of fabric and / or   of continuous and unidirectional fiber webs   glomerated by said thermoplastic matrix, compacting the stack thus obtained under pressure and at a melting temperature of the matrix, solidifying the matrix by cooling to obtain a compacted plate (55), and cutting said laminated element (56) into said plate compacted (55).